Evaluation on the non-isothermal combustion kinetics of lignite and sewage sludge through microwave pretreatment

Abstract

Lignite and sewage sludge powder were pretreated through microwave heating at a power level of 119 W. The non-isothermal combustion characteristics of lignite and sewage sludge powder through the microwave pretreatment were examined based on a thermo-gravimetric technique at three heating rates (10, 20 and 30 °C min−1). The effect of the microwave pretreatment on the combustion performance index and kinetic parameters was addressed. The ignition temperature region of the lignite samples was in between 357 and 376 °C, which was higher than that of the sewage sludge samples ranged from 219 to 235 °C. The comprehensive performance index of the treated lignite and sewage sludge increased by 22.5% and 2.3%, respectively. The combustion kinetic parameters of the samples were evaluated based on KAS method coupled with Criado method. The average activation energies of the untreated lignite and sewage sludge were 213.83 and 176.92 kJ mol−1, while that for the treated samples were 232.64 and 203.01 kJ mol−1.